一二点五乘零点六，减一点吧成零点五简便运算。

12.5×0.6-1.8×0.5
=12.5×0.6-（中则0.6×3）×0.5
=12.5×0.6-0.6×（神培蠢3×0.5）游陪
=12.5×0.6-0.6×1.5
=（12.5-1.5）×0.6
=11×0.6
=6.6

12.5×0.6-1.8×0.5
=12.5×（0.8-0.2）-0.9
=10-2.5-0.9
=10-3.4
=6.6